青藏高原羊八井盆地全新世以来气候变化的泥炭记录

位于青藏高原念青唐古拉山南缘羊八井盆地的七弄沟分布着广阔的泥炭地,通过提取七弄沟泥炭的腐殖化度和总有机碳信息,并结合14C测年控制,反演了全新世9.1~3.5 cal.kaBP羊八井盆地的环境变化信息。根据泥炭记录的古环境特征,将该地区9.1~3.5 cal.kaBP的气候分为3个主要阶段:阶段Ι(9.1~7.4 cal.kaBP)温度波动上升阶段,9.1~7.4 cal.kaBP七弄沟温度呈波动上升趋势,期间发生了两次比较明显的降温事件,分别发生在9.1和8.0 cal.kaBP左右;阶段Ⅱ(7.4~4.7 cal.kaBP)温度波动频繁且剧烈阶段,此阶段七弄沟温度波动频繁且剧烈,在6.0和5.8 cal.kaBP发生了两次比较显著的降温事件;阶段Ⅲ(4.7~3.5 cal.kaBP)温度波动下降阶段,4.7 cal.kaBP之后温度呈波动下降的趋势,但是波动的频率和幅度远比第二阶段小,仅在4.0 cal.kaBP发生了比较显著的降温事件。

PEAT RECORD OF HOLOCENE CLIMATE CHANGE IN THE YANGBAJING BASIN,TIBET PLATEAU

There is a vast peat land in the Qinonggou(QNG) of the Yangbajing Basin next to the southern margin of the Nianqing Tanggula Mountain, Tibet Plateau. By extracting the humification and total organic carbon(TOC)data from the peat in QNG, combined with the 14C dating control, we have reconstructed the Holocene palaeoclimatic variation from 9.1 to 3.5 cal.kaBP at the Yangbajing Basin. On stage I, during 9.1~7.4 cal.kaBP,the temperature showed a fluctuating upward trend. Two obvious cold events occurred in 9.1 cal.kaBP and 8.0 cal.kaBP. On stage Ⅱ, of 7.4~4.7 cal.kaBP, the temperature fluctuation was frequent and intense. Two obvious cold events occurred in 6.0 cal.kaBP and 5.8 cal.kaBP respectively. On stage Ⅲ, during 4.7~3.5 cal.kaBP, the temperature showed a fluctuating downward trend. But the frequency and amplitude of the changes were much tender than those of the second stage. There only occurred a relative significant cold event at 4.0 cal.kaBP.